The invention relates to a concrete block producing device with a block machine having a stone mould that can be fed with fresh concrete from a concrete hopper, wherein the concrete hopper can be filled with portions of at least two differently coloured fresh concretes from a dosing device in a controlled manner and the dosing device has at least two dosing chambers and a transport device to transport the differently coloured fresh concrete portions into the concrete hopper. Further, the invention relates to a method for producing at least two-coloured concrete blocks using such a concrete block producing device according to the invention.
Concrete block producing devices are for the mass production of various parts of concrete like for building construction and/or underground construction, but also for landscaping and/or gardening. The product range of the concrete blocks comprises concrete slabs, paving blocks, curbstones, gutters, and ornamental stones, among others.
Generally, concrete block producing devices as a central plant component have a block machine. Depending on the embodiment these have one or more concrete hoppers. The fresh concrete can be filled from the respective concrete hopper into the stone mould via a feedbox in order to then be packed by means of a vibrator table and a tamper. After the packing operation the product is demoulded and taken out of the block machine on a bolster pallet via a conveyor device.
Concrete blocks that should have a special quality, in particular visual impression, generally consist of a coarse mix layer and an overlying cover layer of facemix that can and should, respectively, form the visible upper surface in the end product. Here, in particular the visible upper surface of a concrete block should often be like the structure and colouring of natural stones. Since the colour pallet of natural stones has a large range a colouring of the concrete stone corresponding to a natural stone requires dyeing of the concrete with different colours. Colours that often occur in nature are black, white, yellow, red, and blue as well as their mixes and shades. In order to fulfill the high customer needs and to generate manifold colour compositions on the concrete stone surfaces several processing stages such as mixing, dosing, and transport must be set.
Generally, a concrete block producing device in addition to at least one block machine has also at least one mixing device for mixing the concrete and generally at least one transport device such as a bucket conveyor plant, a belt conveyor, or the like to transport the fresh concrete from the mixing plant to the block machine or to a dosing device for the fresh concrete. If the device should generate coloured concrete blocks the colour pigments or suitable aggregates are generally admixed to the fresh concrete in the mixing device such that the mostly rather grey colour of the concrete is dyed in a desired colour. In this way, differently coloured concretes can be produced.
In WO 2006/116332 A2 such a generic device and a generic method, respectively, for controlled colour distribution in mass-produced concrete blocks are described, wherein differently coloured fresh concrete portions are specifically inserted into a facemix hopper by means of a dosing and transport device. Here, the dosing device according to WO 2006/116332 A2 has six different dosing chambers storing differently coloured fresh concretes, but wherein also devices with less or more dosing devices are either already known or conceivable. This successively doses the differently coloured fresh concrete portions onto a belt conveyor or simultaneously onto each other if these should already get mixed on the belt conveyor. With the help of this first belt conveyor, also referred to as mixing conveyor, the differently coloured fresh concrete portions are conveyed to a second belt conveyor, the so-called ascending conveyor. Its higher end extends beyond the facemix hopper and is for filling the same. In order to selectively position the differently coloured concrete portions in the hopper the ascending conveyor can be swiveled in a substantially horizontal plane about a vertical axis. Thus, with a central control system various colour patterns can be generated.
This known concrete block producing device is excellent for the production of coloured concrete blocks that should look like natural stones. In particular, it is possible with it to generate exceptionally realistic shades in the concrete blocks. However, it requires relatively large space for the dosing device with its adjacent transport device and is relatively expensive in its manufacture.